1. Field of the Invention
In general, the present invention relates to a communication controlling apparatus and a recording medium for recording communication controlling programs. More particularly, the present invention relates to communication protocol conversion in a data transmission system with a communication protocol on a transmitter side different from a communication protocol on a receiver side.
2. Description of the Related Art
In a data transmission system, data is exchanged among a plurality of communication apparatuses such as SDH (Synchronous Digital Hierarchy) apparatuses through a plurality of communication lines. Normally, an SDH apparatus is provided with a monitoring processing unit for monitoring hardware failures of a communication line interface unit performing the role of an interface between a terminal and a communication line and failures occurring in a received signal. In the event of a failure, alarm information is transmitted to an external monitoring apparatus in accordance with a predetermined communication protocol. Receiving the alarm information, the external monitoring apparatus notifies a person in charge of maintenance of the existence of the failure by outputting the alarm information to a display unit. The person in charge of maintenance then issues a variety of control commands to the communication apparatus through a control processing unit employed in the communication apparatus in order to enhance communication reliability.
With development of an information society going on in recent years, the size of a communication network built to connect communication apparatuses and the amount of data transmitted among the apparatuses through the network keep increasing and, at the same time, up-graded versions of hardware and software are often introduced for improving the functional aspect of each of the communication apparatuses.
As a result, interlocked with the upgrading of the communication apparatus, the monitoring and controlling functions of the external monitoring apparatus are also improved substantially. In some cases, a communication protocol between the communication apparatus and the external monitoring apparatus is also reconstructed.
However, the conventional communication apparatus has only a communication function designed for a fixed communication protocol for communicating with the external monitoring apparatus. As a result, the following problems have been raised.
(a) If a communication network includes communication apparatuses having different communication protocols used for communicating with an external monitoring apparatus, it is necessary to provide a plurality of external monitoring apparatuses to cope with the different communication protocols. As a result, not only does the cost of developing the external monitoring apparatuses rise, but it is also necessary for the user to prepare a plurality of external monitoring apparatuses. That is why the communication network becomes complicated and the cost of its development is skyrocketing. PA0 (b) Even in the case of a communication network built to connect communication apparatuses having a certain communication protocol used for communicating with an external monitoring apparatus, in order to replace the communication apparatuses with those each having new functions and a different communication protocol, it is also necessary to change the external monitoring apparatus with one that keeps up with the new communication protocol. That is to say, it is impossible to replace only the communication apparatus by one having new functions with the external monitoring apparatus kept unchanged.